The prior art recognizes the need for cleaning the nozzle surface of an ink jet printer to remove accumulations of ink and foreign matter, primarily paper fibers, dust and accumulated ink around the nozzle. Such accumulations may clog the very small nozzles through which ink is ejected onto a record, or otherwise affect the dispersal of the ink. Therefore, it has become standard practice to provide some form of wiper for wiping the nozzle surface at intervals during printing and when the printhead is "parked" after printing has been completed.
Two conflicting considerations enter into the design of a wiper. The wiper should be made as hard and wear resistant as possible so that it will not require frequent replacement over the life of the printer. On the other hand, the wiper should be flexible and not so hard as to cause wear of the nozzle surface since the electrical connections leading to the components for causing ejection of the ink are located in the printhead surface being wiped.
An early form of wiper consisted of a generally rectangular beam of elastomeric material located in a maintenance station positioned at one side of the record feed path and extending into the path traversed by the nozzle surface so that the wiper wiped the surface as the printhead moved into, or out of, the maintenance station. A wiper of this type is not efficient in wiping a nozzle surface. The wiping beam tends to accumulate ink between a side of the beam and the nozzle surface, and then rides onto the accumulation so as to leave a thin layer of ink on the surface just wiped.
The problem with the rectangular beam wiper is recognized in U.S. Pat. No. 5,151,715 which attempts to solve the problem by providing two parallel generally rectangular beams, the theory being that the second beam will wipe from the nozzle surface the thin layer of ink left by the first beam. The patent also recognizes that a wiping beam may be made of a harder material and still not cause wear of a nozzle surface if the base portion of the beam is provided with a slot extending through it. U.S. Pat. No. 5,155,497 teaches that the wiper may be mounted for movement into and out of the path traversed by the nozzle surface.
While the wiper disclosed in the aforementioned patents improves wiping efficiency, it is a rather complex structure making it difficult to obtain uniform characteristics among mass produced wipers.